Background: Polydactyly is the most common malformation of the limbs. "Crossed" polydactyly of hands and feet, i.e., preaxial in one and postaxial in the other, is extremely rare. It has not been included in the standard classification of hand and feet anomalies.
Methods: We report an Indian family with 7 affected members across 4 generations who had "crossed polysyndactyly". All but one affected member had involvement of all four limbs. There were no other congenital anomalies in any of the family members.
Results: Familial crossed polysyndactyly appeared to follow an autosomal dominant transmission. This is probably the first case of familial crossed polysyndactyly without any associated anomalies.
Conclusion: Familial crossed polysyndactyly is a rare malformation and all family members should be screened for other congenital malformations.